1. Field of the Invention
This invention relates to a chemical method for separation of uranium isotopes. More specifically, the invention relates to the relative enrichment/depletion of uranium isotopes based on differences (i.e., the presence or absence) of a nuclear magnetic moment and their effects on certain chemical reactions.
2. Description of the Prior Art
It is a well known and well documented fact that in order to convert crude uranium ore having an isotopic distribution of typically .sup.238 U (99.27%), .sup.235 U (0.72%), and .sup.234 U (0.06%) to a useful nuclear fuel, the enrichment of .sup.235 U to a few percent is required. Historically a variety of physical and chemical methods have been suggested and employed for the enrichment of .sup.235 U. In general, these methods have been dependent on differences in the isotopic mass to achieve the separation; i.e., they involve shifts in physical or chemical properties which are mass dependent. For example, in the widely used and traditional gaseous diffusion processes, separations result from the variation of average thermal velocity with mass. However, the mass ratio of .sup.238 U/.sup.235 U is 1.013 and separation based on small differences in mass between isotopes requires a large installation to perform the diffusion or centrifugation techniques. These gas transport techniques also require volatile species, a very restrictive requirement. The separations of specific isotopes from mixtures are generally expensive processes, especially in terms of energy requirements. On the other hand, the new techniques that depend on very small differences in optical absorption frequencies require large, expensive laser facilities and still require volatility.
In a series of related recent technical publications, N. J. Turro and co-workers have demonstrated laboratory scale isotope separation of carbon and oxygen; see for example, N. J. Turro and B. Kraeutler, JACS, 100: 23, 7432 (1978); N. J. Turro, B. Kraeutler, and D. R. Anderson, JACS, 101: 24, 7435 (1979); N. J. Turro and M-F Chow, JACS, 102: 3, 1190 (1980); and B. Kraeutler and N. J. Turro, Chem. Phys. Letters, 70, 270 (1980). They decomposed small organic molecules, with isotope enrichment occurring in the excited state with branching reaction paths leading to chemically separable products. A significant enhancement in the isotope selectively was observed when the transient excited states were confined to micelles. Thus, the article by B. Kraeutler and N. J. Turro in Chem. Phys. Letters, Vol. 70, No. 2 entitled "Photolysis of Dibenzyl Ketone in Micellar Solution: Correlation of Isotopic Enrichment Factors with Photochemical Efficiencies Parameters", discloses the enrichment of carbon-13 over carbon-12 by the photolysis of dibenzyl ketone using the fact that carbon-13 has a magnetic moment. Similarly, the use of magnetic nuclear moment to separate oxygen-17 from oxygen-16 and -18 is disclosed in the article by N. J. Turro and M-F Chow, entitled "Magnetic Isotope Effect on the Thermolysis of 9,10-Diphenylanthracene Endoperoxide as Means of Separation of 17 Oxygen from 16 Oxygen and 18 Oxygen" in the JACS, Vol. 102; 3, Jan. 30, 1980, pages 1190 to 1192. In a recent Science article, Vol. 206, Oct. 19, 1979, T. H. Maugh reviewing several of the previous free radical 9,10-diphenylanthracene endoperoxide reactions by N. J. Turro speculates that "the same principle can be applied to any other magnetic isotope, including, presumably, uranium-235, if an appropriate chemical reaction can be found." However, to the best of our knowledge, no such reaction schemes for uranium isotope enrichment have been published.